a pictures worth a thousand words

[13Echo70271]

could a po have started with a black/white pos/neg system and only changed the white wire (incorrectly) to red? some boats have been wired that way blk=pos , wht = neg .
electricians show those types of changes with the correct color tape on the last few inches of each end of a single line to prevent mix-ups. My v20 came to me with a bunch of that orange wire also. It took a while to trace all.

[Troutkiller2006]

red is hot, and should be on the left side, at the bottom in that picture. all the other screws on the left side, other than the "hot in" at the bottom, only purpose is to connect the fuses to the "hot bar" and energize them, no wires should be attached to those screws. the middle run of screws, just to the right of the fuses, are the energized connections coming out of the fuses and all "positive out" leads should be connected there. they are not even used in the picture! the bottom screw on the right, where the po has connected the "positive in" power supply wire is actually the negative grounding buss and is meant to connect all ground wires.

the result of the way this thing is wired is the same as if all the hot wires were just twisted together and if all the negative wires were just twisted together and there wasnt a fuse box at all. everything hooked up to it will turn on but WILL NOT BE FUSE PROTECTED. so if there is a short somewhere instead of a fuse blowing and shutting off the power to the short, the shorted wire will remain energized, get very hot, possibly start sparking, probably do a lot of damage and might even make you jump out of your boat so you can tread water and watch it burn!

[Lance Pearson]

I have a 1977 and bought a new negative buss to mount behind the dash and a new positive with spade fuses buss and intend to run the negative black to that buss then the positive red to that buss from the battery and distribute a negative to each electric device from the buss and after the fuse, a red + to each device so it goes through the fuse on the positive, red side. That's the way I remember my big sailboat was wired and I hate those round glass tube fuses. Modern spade fuses are much easier. If my thinking is backward let me know. I have not crawled into the cuddy yet to check it out, just know I want different at this point. I chose to have a separate negative buss which I'll mount and bring one heavy wire from battery to it and then a separate with spade fuses positive (red) buss with a heavy red wire from the battery. From that I will run a black to one side of a switch or device and after the fuse a red to the other side of same switch or device. It's like a loop and the fuse goes into the red side of the loop. I'm quite content with two separate busses unless I've completely forgotten how to do this.

[Lance Pearson]

This diagram is how I plan to do mine. The wires in place I will trace with power source and meter/probe, label then run from battery to the busses forward then to each device from the busses through the fuses.